1. Field of Invention
This invention relates to a spray head for high pressure airless spraying and, in particular, to a spray head capable of handling very highly loaded suspensions and mastic compositions as well as low viscosity liquids.
2. Brief Statement of the Prior Art
Airless spraying of liquids is widely practiced, particularly for professional spray applications of paints, lacquers and the like. Typically, these liquids are sprayed under pressures of from 500 to 3,500 psi through minute orifices of highly wear-resistent material such as tungsten carbide.
A difficulty commonly experienced is the clogging of the spray tips with solids and this problem becomes particularly acute when attempting to spray liquids which are highly loaded with solids, such as mastic compositions. Typical of such compositions are fire-proofing compositions, water-proofing coating compositions, and asbestos encapsulating coating compositions. These compositions can have as high as 85 weight percent solids. The solids are frequently very abrasive, e.g. clays, silica, sand and the like. Difficulty is experienced when spraying such highly loaded compositions with airless spraying equipment because of the highly erosive character of the compositions and because the solids clog the orifices commonly used in airless spray equipment.
It is desirable to provide a spray head useful in an airless spray gun that would handle the highly viscous and erosive compositions while not compromising the ability of the spray head to spray low viscosity liquids such as stains, lacquers, sealers alkyl enamels, and water-base paints and enamels.